1. Field of the Invention
The present invention relates in general to a detecting element, and more particularly to a detecting element utilizing temperature dependence of an electrically resistive body, such as a thermal flow meter suitable for determining, for example, a flow rate or velocity of a fluid flowing in an internal combustion engine.
2. Discussion of the Prior Art
A detecting element such as a thermal flow meter which utilizes temperature dependence of an electric resistor is known. An example of this type of detecting element is disclosed in laid-open publication No. 56-96326 of unexamined Japanese Utility Model Application. This detecting element includes a heat-generating electrically resistive body formed on a support in the form of a tube or rod. Electrical conductors or leads which are electrically connected to the resistive body are secured to opposite ends of the support, by using a platinum paste, so that the strength of the connections between the conductors and the support is increased to improve the durability of the detecting element.
A flow meter employing the detecting element of the type described above suffers from a problem that heat produced by the resistive body, which should be dissipated into a fluid to be measured, tends to be transferred to or absorbed by the conductors, since a material such as a platinum paste having a comparatively high thermal conductivity is interposed as a bond between the conductors and the support which bears the resistive body. This tendency leads to reduced detecting accuracy of the meter because the temperature of the resistive body does not accurately correspond to the flow rate or velocity of the fluid to be measured. Further, the above tendency increases an initial operating time between the moment of commencement of energization of the electrically resistive body and the moment at which the detecting accuracy of the meter is stabilized.